Steam-Generator Furnace

ABSTRACT

The invention relates to furnace devices for powerful power-generating units and can be used for the heat and electric-power industry. The inventive steam-generator furnace comprises a vertical annular combustion chamber, which is formed by external and internal tubular screens, embodied in the form of concentrically arranged equilateral prisms. Burners and secondary air nozzles are placed in the bottom part of the furnace on the external screen faces tangentially to a conventional circle. Said burners and nozzles are movably arranged on the same plane and unidirectionally oriented in such a way that it makes it possible to adjust the conventional circle diameter. Additional secondary air nozzles are mounted in the top part of the furnace on the faces of the external and internal screens oppositely with respect to the burners.

The utility model relates to furnace systems in heavy-dutypower-generating units, and can be used in the thermoelectric powerindustry.

Known in the art is a boiler furnace consisting of internal and externaltubular screens that are designed as two concentrically mounted,equilateral prisms, wherein burners are set up on each face of the lastof the screens tangentially to some conditional periphery (RU 909418,F23C 5/08, 1982).

In one known device for generating a vortical furnace flame for aspecific type of fuel, the burners must be arranged in a specific mannerrelative to the screens. Since the burners are fixed in place in theknown device, the latter is strictly “tied” to a specific type and evensort of fuel, which is one of its practical shortcomings.

Known in the art is a steam generator furnace (RU 953366, F23C 5/08,1982) with a vertical annular combustion chamber consisting of externaland internal tubular screens that are designed as concentricallymounted, equilateral prisms, wherein the lower portion of the screenface incorporates respective tangential burners and secondary airnozzles, with the latter being mounted in line with the burners.

Just as the analog described above, the known furnace is critical to thetype of used fuel, which is one of its shortcomings.

A known technical solution involving nozzles arranged on the outer wallof the furnace involves the supply of all secondary air introduced intothe furnace apart from the burners. This diminishes the heat absorptionof the internal screen and, as a result, reduces furnace efficiency,which is a second of its shortcomings.

Feeding all secondary air into the lower portion of the furnaceincreases emissions of nitrogen oxides, which is also a shortcoming withrespect to the known technical solution.

In addition, given the relatively high temperature of the exiting gasescaused by the reduction in heat absorption of the screens, the furnacehas large dimensions, and requires elevated capital expenditures foroutfitting purposes.

The proposed utility model resolves the task of eliminating theaforementioned shortcomings using a specific furnace design.

According to the technical results obtained, various types of fuel canbe optimally combusted, furnace efficiency can be increased, nitrogenoxide emissions can be cut, and furnace dimensions can be cut.

The technical results are achieved by virtue of the fact that burnersare movably incorporated in the steam generator furnace with a verticalannular combustion chamber consisting of internal and external tubularscreens that are designed as concentrically mounted, equilateral prisms,wherein the lower portion of their faces accommodates burners tangentialto the conditional periphery, and secondary air nozzles, making itpossible to regulate the diameter of the conditional periphery within arange of 0.4-0.7 D, where D is the diameter of a periphery entered inthe cross section of the prism of the external screen, and the secondaryair nozzles are mounted on two tiers over the height of the furnace.

The first tier of secondary air nozzles is located at the burner levelon the faces of the external screen, while the second tier is situatedin the upper portion of the furnace on the faces of the external andinternal screens; the nozzles in the first tier are directed in linewith the burners, while those in the second run counter to the burners.

FIG. 1 presents a vertical section of the claimed furnace, while

FIG. 2 shows a section AA of FIG. 1.

The furnace contains a combustion chamber 1, external screen 2 andinternal screen 3, secondary air nozzles 5 (first tier) and 6 (secondtier).

The furnace operates as follows.

The fuel-air mixture passes through the burners 4 into chamber 1, wherethey undergo combustion. To provide optimal aerodynamics for thevortical furnace flame that ensure efficient fuel combustion whileprecluding any active influence of the flame on the screen, the burnersare mounted tangentially to some conditional periphery, the diameter ofwhich depends on the physicochemical properties of the fuel.

Movably mounting the burners makes it possible to regulate the diameterof the conditional periphery, and thereby optimize the combustionconditions for a specific sort of used fuel. In the proposed device, therange of regulation measures 0.4-0.7 D, where D is the diameter of aperiphery entered in the cross section of the prism of the externalscreen, which ensures an efficient, optimal combustion of coal frompractically all known coal deposits.

The secondary air nozzles 5 set up on the furnace faces at the burnerlevel create a system of incremental horizontal secondary air supply,which provides the furnace with a symmetrical aerodynamic whileeliminating individual grinders and lowering NO_(x) emissions. Tominimize the danger of slag formation on the external screens of thefurnace and improve conditions for aeromixture combustion, the burnersare set up in such a way that the aeromixture jet exits on the side ofthe flame, while the secondary air jet exits form the external screen.

The secondary air nozzles 6 set up in the upper portion of the furnaceon the second tier ensure that the residual twists of exiting gases areextinguished, and consequently, that the heating surfaces in the gasduct are uniformly cleaned.

In addition, the counter-motion of the recycled air from nozzles 6effectively lower the temperature of the exiting gases, which furtherlowers NO_(x) emissions, and also enables a reduction in the number ofgas ducts, and ultimately, furnace dimensions.

The table below presents comparative technical and economic indices forfurnace assemblies based on the proposed furnace and a known furnace.

TABLE Known boiler furnace, Claimed furnace type P-67 (800 MW (for 800MW boiler) Berezovskii GRES unit) Surface of heated, 67 100 all-weldedscreens, % Total heated surface 78 100 under pressure, % Dimensions ofboiler, m Width along front 27.5 55.0 Depth 27.5 22.8 Height 63.0 90.0Mass of boiler 96 100 with frame, % Specific volume of 0.811 1.142construction for the 71 100 main body, (m³/kW)/%) Cost of structural 60100 section, % Cost of 1 kW 86 100 installed power, %

An analysis of data on the table shows that using the proposed furnacemakes it possible to significantly reduce the weight and dimensionalcharacteristics of the furnace, decrease its metal intensiveness andconstruction costs, which in the final analysis lowers the specific costof energy produced.

1. A steam generator furnace with a vertical annular combustion chamberconsisting of external and internal tubular screens that are designed asconcentrically mounted, equilateral prisms, wherein the lower portion ofthe screen face incorporates burners situated tangentially to aconditional periphery, and secondary air nozzles, characterized in thatthe burners are movably mounted with the capability of regulating thediameter of the conditional periphery, and the secondary air nozzles arearranged over the furnace height in two tiers.
 2. The steam generatorfurnace according to claim 1, characterized in that the range ofregulation for the conditional periphery measures 0.4-0.7 D, where D isthe diameter of the periphery entered in the cross section of the prismof the external screen.
 3. The steam generator furnace according toclaim 1, characterized in that the first tier of secondary air nozzlesis located at the burner level on the faces of the external screen. 4.The steam generator furnace according to claim 3, characterized in thatthe nozzles are directed in line with the burners.
 5. The steamgenerator furnace according to claim 1, characterized in that the secondtier of secondary air nozzles is situated in the upper portion of thefurnace on the faces of the external and internal screens.
 6. The steamgenerator furnace according to claim 5, characterized in that thenozzles run counter to the burners.